A higher proportion of n-3 long-chain PUFA in tissue lipids has been associated with a lower risk of CVD and some cancers. Diet is an important predictor of n-3 long-chain PUFA composition; however, the importance of non-dietary factors such as sex and age is unclear. We measured the proportion of n-3 long-chain PUFA in serum phospholipid, cholesterol ester and TAG of 2793 New Zealanders 15 years or older who participated in the 1997 National Nutrition Survey to determine differences by sex and age. Women had lower proportions of EPA and docosapentaenoic acid in phospholipid, by 0·07 (P = 0·004) and 0·10 (P < 0·001) mol%, respectively, and a higher proportion of DHA by 0·16 mol% (P = 0·001) compared with men. Intake of fish fat did not differ between men and women. There was a positive association between age and the proportion of EPA and DHA in phospholipid (P < 0·001). The sex differences in EPA and DHA were similar at all ages. Similar sex and age differences in serum cholesterol ester n-3 long-chain PUFA were found; only age differences were found in serum TAG. Sex and age differences in n-3 long-chain PUFA occur in the general population. Men and women may need to be considered separately when examining the association between disease risk and biomarkers of n-3 fatty acids.

A number of methods have been developed to assist subjects in providing an estimate of portion size but their application in improving portion size estimation by children has not been investigated systematically. The aim was to develop portion size assessment tools for use with children and to assess the accuracy of children's estimates of portion size using the tools. The tools were food photographs, food models and an interactive portion size assessment system (IPSAS). Children (n 201), aged 4–16 years, were supplied with known quantities of food to eat, in school. Food leftovers were weighed. Children estimated the amount of each food using each tool, 24 h after consuming the food. The age-specific portion sizes represented were based on portion sizes consumed by children in a national survey. Significant differences were found between the accuracy of estimates using the three tools. Children of all ages performed well using the IPSAS and food photographs. The accuracy and precision of estimates made using the food models were poor. For all tools, estimates of the amount of food served were more accurate than estimates of the amount consumed. Issues relating to reporting of foods left over which impact on estimates of the amounts of foods actually consumed require further study. The IPSAS has shown potential for assessment of dietary intake with children. Before practical application in assessment of dietary intake of children the tool would need to be expanded to cover a wider range of foods and to be validated in a ‘real-life’ situation.

For food intakes to be converted into nutrient intakes a measure or estimate of the amount of food consumed is required. A number of methods have been developed to assist subjects in providing an estimate of portion size. Children's ability to use perception, conceptualisation and memory skills to estimate food portion size has not been investigated systematically. The aim of the present study was to test the effect of the timing of a dietary interview on the accuracy of estimates of food portion sizes made by children, using food photographs, food models and an interactive portion size assessment system, developed for use with children and based on portion sizes of foods consumed by children. Children (n 108) aged 4–14 years were supplied with known quantities of foods and asked to estimate the portion size of each food using each of the three portion size assessment tools. Interviews took place (a) with the food in view, (b) just after the child had eaten the food or (c) 24 h after the child had eaten the food. There were no significant differences in children's ability to estimate food portion size (either as served or as eaten) with timing of interview. That is, children were as accurate in their estimates of portion size 24 h after consuming the food as when the food was in view. Under these conditions many children were able to estimate food portion size utilising perception, conceptualisation and memory skills.

Since any significant modification in the Se status, leading to changes in the activity of the seleno-enzymes, may have important consequences on the susceptibility of tissues to oxidative stress, considerable efforts have been made upon increasing Se dietary intake. In this respect, an important debate is still open about the bioavailability and the effectiveness of Se, and more generally nutrients, in supplements compared with foods. Using male Wistar rats, we have compared the effectiveness of two different diets in which an adequate Se content (0·1 mg/kg) was achieved by adding the element as sodium selenite or as component of a lyophilized Se-enriched food, in the counteraction of an oxidative stress induced by intraperitoneal administration of adriamycin. Both Se-enriched diets were able to reduce the consequences of the oxidative stress in liver, mainly by increasing glutathione peroxidase activity. This increase was more evident in rats fed on the diet enriched with the lyophilized food, probably due to the different chemical forms of Se, or to other components of the food itself. Although further studies are needed, data herein presented may contribute to the characterization of the effectiveness of Se from different sources, foods or supplements, in the light of dietary advice to the population concerning improvement of Se intake.

The UK Food Standards Agency convened an international group of expert scientists to review the Agency-funded projects on diet and bone health in the context of developments in the field as a whole. The potential benefits of fruit and vegetables, vitamin K, early-life nutrition and vitamin D on bone health were presented and reviewed. The workshop reached two conclusions which have public health implications. First, that promoting a diet rich in fruit and vegetable intakes might be beneficial to bone health and would be very unlikely to produce adverse consequences on bone health. The mechanism(s) for any effect of fruit and vegetables remains unknown, but the results from these projects did not support the postulated acid–base balance hypothesis. Secondly, increased dietary consumption of vitamin K may contribute to bone health, possibly through its ability to increase the γ-carboxylation status of bone proteins such as osteocalcin. A supplementation trial comparing vitamin K supplementation with Ca and vitamin D showed an additional effect of vitamin K against baseline levels of bone mineral density, but the benefit was only seen at one bone site. The major research gap identified was the need to investigate vitamin D status to define deficiency, insufficiency and depletion across age and ethnic groups in relation to bone health.

I did not intend to revisit the discussion of the publication of Brandolini et al.1 on Ca urinary excretion attributed to the sulfate content of water but in their answers2 to my comments3, they said that ‘I accept their experimental results’ and that ‘I do not contest the difference in calciuria between milk and sulfate-rich water’. I never wrote that I agree with their results and even more with their conclusions but questioned how is it possible to evaluate a 20 mg difference in daily Ca urinary excretion from a study with subjects under uncontrolled dietary intakes, unbalanced experimental study design and without analytical results on acid–base balance and sulfate to support their acidogenic hypothesis of sulfate. I did not find any convincing explanations in their answers but I want to raise several points of disagreement, which are either repeated or new.

Zafeiridis et al.1 recently described the effects of resistance exercise on postprandial TAG concentrations. Zafeiridis and colleagues observed a reduction in 6 h total and incremental TAG area under the curve concentrations after resistance exercise protocols expending approximately 0·76 and 1·40 MJ.

We thank Drs Burns and Stensel for their interest in our work. We agree that the published articles on the delayed effect of resistance exercise (RE) on postprandial lipaemia (PL) provide controversial results. Three studies1–3 employed comparable methodologies in terms of exercise protocol and feeding plan of the subjects, that is, two to four sets of eight to eleven exercises at relatively similar intensities (about 10–12 repetitions maximum (RM)) with 1·5–2·0 min of rest between sets and a standardised meal on the night prior to the fat tolerance test. These studies reported a decrease1,3 or no change2 in the postprandial lipaemic response. A fourth study4 employed a similar RE protocol but focused on maintaining the subjects in a state of energy balance by increasing food intake up to two-fold after RE v. control on the night prior to the fat tolerance test. This study found no significant effect of RE on PL.